Multiple retrieval system for objects in submarine environment

ABSTRACT

A multiple retrieval system for objects placed on the sea floor for extended periods of time comprising holding means and three retrieval means. The first retrieval means is a vertical line system, the line being fabricated of titanium monofilament fastened to a cast-steel ball anchor at the lower end and a syntactic-foam globular buoy at the upper end which is some 50 feet below the ocean surface. The second retrieval system comprises a 5200-foot length (approximately) of polypropylenejacketed, aluflex line extending from said cast-steel ball anchor to a frame for holding the submerged object. The third retrieval system comprises a 5,000-foot length (approximately) of polypropylene, self-buoyant rope extending from the frame to another cast-steel ball anchor.

United States Patent Aleksander B. Macander Jersey City, N.J.; Clarence K; Chatten, Jackson Heights, NJ.

[72 Inventors 3,082,608 3/1963 Daniell 3,293,867 12/1966 Dean Primary Examiner-Andrew H. Farrell Attorneys- Louis A. Miller, Louis B. Applebaum and Philip Schneider ABSTRACT: A multiple retrieval system for objects placed on the sea floor for extended periods of time comprising holding means and three retrieval means. The first retrieval means is a vertical line system, the line being fabricated of titanium monofilament fastened to a cast-steel ball anchor at the lower end and a syntactic-foam globular buoy at the upper end which is some 50 feet below the ocean surface. The second retrieval system comprises a 5200-f0ot length (approximately) of polypropylene-jacketed, aluflex line extending from said cast-steel ball anchor to a frame for holding the submerged object. The third retrieval system comprises a 5,000-foot length (approximately) of polypropylene, self-buoyant rope extending from the frame to another cast-steel ball anchor.

MULTIPLE RETRIEVAL SYSTEM FOR OBJECTS SUBMARINE ENVIRONMENT The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to retrieval systems for objects which are submerged in a submarine environment for long periods of time.

Due to the increased interest in underwater exploration and oceanic potentialities for the future of mankind, a great deal of experimental work has been going on relative to the characteristics of materials when exposed to sea water for lengthy periods of time. The materials to be tested are often placed in an opening holding means such as a rack or framework, lowered to the sea floor and left for periods extending up to five years or more.

When the test period has expired, the framework containing the test materials must be recovered from the ocean floor. However, it is often found that it is difficult to find and retrieve the framework, frequently because the mooring lines cannot be located or because they have deteriorated and break when subjected to tension.

An object of the invention is, therefore, to permit reliable retrieval of an object which has been left on the ocean floor for an extended period of time.

Another object is to provide a corrosion-resistant retrieval system.

The objects and advantages of the present invention are accomplished by provision of a three-way retrieval so that the main retrieval system, which is a vertical line with a buoy, is backed up by two bottom lines, one of which is self-buoyant. The materials from which the lines are fabricated are chosen with a view to corrosion and deterioration resistance.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic illustration of an embodiment of the invention; and

FIG. 2 is a schematic illustration of one type of fastening means for the titanium cable.

The first retrieval system, the vertical system, comprises a buoyant sphere or buoy 12, a short length of line 16, a long length of line 20 and an anchor 24. Fastening means 14, 18 and 22 are used to tie the various components together.

The approximate dimensions and lengths which are included herein are typical for an ocean depth of about 4200 feet and can be altered for other ocean depths.

The buoy 12 was made from syntactic foam and is in the shape of a sphere having a 2 feet 6 inch diameter. This gives sufficient buoyancy to support the weight of the vertical line suspended from the buoy 12.

The short length of line, or the leader cable 16, is a steel cable coated with aluminum and is about 100 feet long and three-eighths inch thick.

The long line, which can be called the vertical line, 20 is a titanium monofilament about 4200 feet in length and 0.l22 inches thick. Titanium monofilament was chosen in particular because of its excellent anticorrosion properties and its high strength-to-weight ratio.

The anchor 24 may comprise a cast-steel ball. The particular one used in this embodiment weighs about 320 pounds in sea water.

Because of galvanic-action corrosion problems, the titanium monofilament cable 20 is terminated at both ends with the special fastening means 18 shown in FIG. 2. This fastening means 18 utilizes one or more crimped oval sleeves 50 (also known as Nicopress oval sleeves, to clamp the cable end to the cable 20. A plastic (e.g., lucite) mold 52 is placed around the cable and sleeves and the cavity filled with epoxy 54. The encapsulation is necessary to prevent galvanic corrosion (dissimilar metal galvanic action) since the sleeves 50 are made of copper and are in direct contact with the titanium.

The titanium cable 20 loops around a plastic (e.g., lucite) shackle bearing 56 which insulates it from the metal of the leader cable 16. The latter is connected to the shackle bearing 58 by being looped through a shackle 58 which may be made of galvanized steel.

The reason for the use of the leader cable 16 is that encapsulation of the titanium cable termination takes some time to accomplish, whereas the coupling of the leader cable 16 can be accomplished quickly. Thus, the titanium cable 20 and its fittings are prepared beforehand and the fastening of the leader cable fittings is done at sea.

If other types of fittings are used which can be quickly made or if corrosion can be tolerated because the time of submergence is not too long, the leader cable 16 can be eliminated and only the titanium cable used.

The second retrieval system comprises a five-sixteenths inch thick aluminum-coated steel cable 28 about 5200 feet in length and fastening means 26 and 30 to fasten the line to the anchor 26 at one end and the exposure frame, or rack, 32 at the other. The cable 28 is further coated with polypropylene so that its outside diameter is one-half inch. The polypropylene provides extra protection to the cable and some buoyancy to reduce its weight in water, although not enough to float the cable 28.

The length of the horizontal cables is primarily a function of the depth of the water, the speed of the surface vessel when it lays the equipment and the rate of underseas currents in the area. At a minimum, the distances between the rack and the anchors should probably be no less than about 1000 feet so that the cables can be found without too much difficulty, taking into consideration the accuracy of present-day navigation systems.

The third retrieval system comprises a braided polypropylene line 38 and an anchor 42 with appropriate fastening means 36 and 40 to tie the line 38 to the exposure rack 32 and the anchor 42. The line 38 is about 5000 feet in length and about five-eighths inch thick. The polypropylene is buoyant so that the line floats in a curved attitude above the sea bottom 44. This type of material is highly resistant to corrosion and to attack by marine organisms. The anchors 42 and 24 are the same in this embodiment.

The exposure rack 32 is any type of frame suitable for supporting the items 34 whose characteristics are to be tested under submergence conditions.

A good material to use for the rack is aluminum since it is light in weight and has good corrosion resistance.

In recovering the rack 32, the recovery vessel first searches for the buoy 12 by sight after coming to its approximate location by navigation techniques. If the buoy is located, divers are sent down to attach a cable to the buoy and the assembly is then pulled up. If the vertical retrieval system has broken at some point, grapples are used to locate one of the two horizontal retrieval lines 28 and 38, after which the rack is pulled abroad.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

We claim:

1. A system for retrieving an object which is placed and left on the ocean floor for a period of time comprising, in combination:

first retrieval means comprising:

anchor means,

a first cable consisting of a length of seawater-corrorionresistant material,

buoy means, and

means for fastening said cable to said anchor means at one end and to said buoy means at the other end;

second retrieval means comprising:

a second cable consisting of length of seawater-corrosionresistant material, and

means for fastening said second cable to said anchor means at one end and to said object at the other end, said buoy means having sufficient buoyancy to support said first cable in a vertical position; and third retrieval means comprising:

a third cable consisting of a length of self-buoyant, seawater-corrosion-resistant material, second anchor means, and means for fastening said third cable to said object at one end and to said second anchor means at the other end. 2. A system as in claim 1, wherein said first, second and third cables are all fabricated from different materials.

3. A system as in claim 1, wherein said first cable is fabricated from titanium, said second cable from aluminumcoated steel covered with a jacket of polypropylene, and said third cable from braided polypropylene.

4. A system as in claim 1, wherein said first cable is of such length that said buoy means lies approximately 50 feet below the ocean surface.

5. A system as in claim 1, further including sea-water-corrosion-resistant leader cable means fastened between said buoy means and said first cable, the length of said leader cable means being short in comparison to that of said first cable.

6. A system as in claim 1, wherein the lengths of said second and third cables are sufficient to provide at least a IOOO-foot separation between their respective anchor means and said object. 

2. A system as in claim 1, wherein said first, second and third cables are all fabricated from different materials.
 3. A system as in claim 1, wherein said first cable is fabricated from titanium, said second cable from aluminum-coated steel covered with a jacket of polypropylene, and said third cable from braided polypropylene.
 4. A system as in claim 1, wherein said first cable is of such length that said buoy means lies approximately 50 feet below the ocean surface.
 5. A system as in claim 1, further including sea-water-corrosion-resistant leader cable means fastened between said buoy means and said first cable, the length of said leader cable means being short in comparison to that of said first cable.
 6. A system as in claim 1, wherein the lengths of said second and third cables are sufficient to provide at least a 1000-foot separation between their respective anchor means and said object. 